1. Field of the Invention
The present invention relates to a semiconductor laser device and a method for producing the same.
2. Description of the Related Art
T. Takiguchi et al., “1.3 μm Uncooled AlGaInAs-MQW DFB laser with λ/4-shifted Grating” Proceedings, Optical Fiber Communication Conference and Exhibit 2002, ThF3, pp. 417-418 (Non-Patent Reference 1) describes a ridge-type semiconductor laser device having a diffraction grating. In this semiconductor laser device described in this reference, the diffraction grating is formed inside a ridge on the upper side of an active layer.